Antigen receptors and adhesion molecules on T lymphocytes in the gut

The gut-associated lymphoid tissue represents an important site of initial contact with foreign antigens from the intestinal lumen. It is a complex immune system comprising of Peyer's patches, mesenteric lymph nodes, mucosal lymphocytes present in the lamina propria, and intraepithelial lymphocytes located on the luminal surface of the basement membrane and adjacent to the basolateral side of enterocytes. The function and immunoregulation of the gut-associated lyphoid tissue and its role in the pathogenesis of intestinal diseases are only partly understood. We summarize selected advances in understanding the cell-surface molecules involved in homing and adhesion of T cells in the gut-associated lymphoid tissue and the nature of the T-cell antigen receptor repertoire expressed by intraepithelial lymphocytes.